1. Field of the Invention
The present invention relates to a weld checking apparatus for a laser or spot welding machine, which allows a worker to check a weld state in the course of the welding process, and more particularly, to a weld checking apparatus for a welding machine that allows a worker to precisely see the weld state with the naked eye while protecting the worker's eyes from strong light such as a flash and plasma that are generated in the course of a laser or general spot welding process.
2. Description of the Related Art
Generally, there are a variety of welding methods. In recent years, among these welding methods, laser welding appears on the stage instead of spot welding.
Welding with a spot welding machine is performed with a welding head contacting a welding object in a state where electric power is applied to the welding object. However, the laser-welding machine makes it possible to realize non-contact high speed welding. The laser welding machine is designed such that a laser beam generated by an oscillator is triggered to a welding object through an output adjusting lens and a plurality of prisms in a welding head, in which the oscillator and other required parts are disposed, to perform precise welding. The output of the laser beam during the welding is adjusted by varying an angle of the output adjusting lens with respect to an advancing axis of the laser beam.
When a welding object is welded by a laser beam triggered from a non-contact type laser welding machine or by electric power applied from a contact type spot welding machine, a strong light such as a flash or plasma is generated. Particularly, since the laser welding machine performs precise welding by one or scores of beam triggers per minute, it is impossible for a worker to weld while checking the weld state with the naked eye due to the strong light of the beams.
Accordingly, in recent years, a weld checking apparatus for checking the weld state during laser welding or spot welding in an automatic production line has been developed on a commercial scale.
The weld-checking apparatus comprises a relay switch coupled to an output side, the relay switch outputting a switching signal when the laser or spot welding is performed, and a display part for displaying the number of times the welding is performed, i.e., the number of welds, by receiving a switching signal from the relay switch. Such a weld-checking apparatus is installed on a robot for performing the laser or spot welding in an automatic production line, notifying a worker only how many times the welding is performed.
That is, the weld-checking apparatus is designed to display the number of times the welding was performed whenever laser welding or spot welding is processed in an automatic production line. Therefore, it is impossible for the worker to check whether the robot is correctly welding the welding object. As a result, after a large number of welding objects are welded by the robot, the worker must examine the welded portions of the objects with the naked eye to determine if there are any bad welds. When there is bad welding on the object, it must be re-welded using the robot, which is troublesome for the worker. Furthermore, since the re-welded portion is not smooth, it may be easily damaged.
Particularly, when precise manual laser welding is required without using a robot, it is impossible for the worker to check the weld state in the course of the welding process due to a strong light such as a flash, plasma, and the like that are generated during the welding process. Therefore, the worker must check the welded portion with the naked eye after each unit welding process is finished. This must be repeated until the entire welding process is finished, deteriorating the advantage of the laser welding that can realize the non-contacting high speed welding. Furthermore, since it is impossible to check the weld state while performing the welding process, the weld is not precise and is unevenly realized.